Question

A soil has porosity of 30%. Its voids ratio in the loosest and densest state is 0.35 and 0.92 respectively. What will be its density index?

(a) 0.865

(b) 0.872

(c) 0.861

(d) 0.881

The question was posed to me in final exam.

Enquiry is from Density Index and Relative Compaction topic in chapter Preliminary Definitions and Relationships of Geotechnical Engineering I

Answer 1

The correct answer is (c) 0.861

For explanation: Given,

Porosity of 30%=0.3

voids ratio in the loosest state emin= 0.35

voids ratio in the densest state emax=0.92

e=\(\frac{n}{(1-n)}\)

e=\(\frac{0.3}{(1-0.3)}\)

e=0.429

ID=\(\frac{(e_{max} – e)}{(e_{max}-e_{min})}\)

ID=\(\frac{(0.92 –0.429)}{(0.92-0.35)}\)

ID= 0.861.